80 PROCEEDINGS OF THE ACADEMY OF [1883. 



The families included in tliese suborders will be the following : 

 Tjeniodonta. Galamodontidse ; Ectoganidse. 

 TiLLODONTA. Tillotheriidae. 

 Daubentonioidea. Ghiromyidse. 

 Prosimi^. Tar Slid ae ; (?) Anaptomorphidse ; (?) Mixodectidse; 



Lemuridse. 

 Insectivora. Soricidse ; Erinaceidse ; Macroscelidse ; Tupaeidse ; 



Adapidse ; ^ Arctocyonidse. 

 Creodonta. Talpidae ; Ghrysochlorididse ; Esthonyvhidae; Gen- 



tetidde { = Leptictidae dim); Oxysenidse ; Miacidse ; Amblyc- 



tonidse ; Mesonychidas. 



I at one time called this order bj'^ the name Insectivora, a course 

 which some zoologists may prefer. But a name should as nearlj^ 

 as possible adhere to a group to which it was first applied, and 

 whose definition has become currently associated with it. Such 

 an application is correct in fact, and is a material aid to the 

 memory. There are various precedents for the adoption of a new 

 general term for a group composed of subordinate divisions which 

 have themselves already received names. 



In order to determine the number of internal tubercles in some 

 of the Liseclivora, so as to ascertain the affinities of some ques- 

 tionable genera, it is first necessary to examine the homologies 

 of the cusps of the molar teeth. The opossums are characterized 

 by the presence of three longitudinal series of tubercles on the 

 superior molar. The homologies of these cusps are rendered 

 clear by the character presented by the fourth superior premolar, 

 where the anterior intermediate is wanting. The external cusps 

 are really such, and are not developed from a cingulum external 

 to the true external cusps, as appears at first sight to be the case 

 with such animals as the Talpidae. The intermediate cusps are 

 really such, although the posterior looks like the apex of a V- 

 shaped external cusp. In Peratherium the external cusps are 

 smaller than in Didelphys, and the intermediate Vs so much 



' Two species of Pelycodus must be removed from this genus and family, 

 and be placed in the Creodonta with Miodcenus. They are the P. pelv/dens 

 and P- angulatus, which have the posterior inner tubercle of the superior 

 molars, a mere projection of the cingulum. I place them in a new genus 

 which differs from MioclcBnus in the possession of an internal cusp of the 

 fourth inferior premolar, under the name of Chriacus ; type C. pelvidens. 



